1. Field of the Invention
This invention generally relates generally to medical safety devices and in particular to a disposable safety needle having an enclosure means.
2. Description of the Related Art
Fluid collection sets, catheters, and intravenous infusion sets are typically used to collect bodily fluids from a patient or to infuse liquids into a patient. These devices typically include a length of flexible plastic tubing with a proximal end connected to a plastic fitting and a distal end connected to a needle, or in the case of a catheter, a tubular assembly. In practice, fluid is transferred via the plastic tubing either to or from the needle or tubular assembly.
Accidental sticks with a needle cannula can be not only painful but can also transmit disease from a patient to medical personnel. Similarly, catheters may retain fluids when they are removed from a patient and transmit disease via these fluids if passed to medical personnel. As a result, nearly all needle assemblies and other sharp medical implements are employed with an apparatus for enclosing the sharp tip of the needle or tubular assembly both prior to and after use.
Protection prior to use is typically achieved by a rigid plastic tube that surrounds a portion of the needle including the sharp edge. This rigid tube typically has a proximal end frictionally mounted to or near the hub and a distal end that extends beyond the distal end of the piercing element. The rigid tube itself surrounds the needle and prevents contact with the needle point until it is removed. Once removed, the plastic tube is discarded immediately prior to use of the piercing element.
One prior art form of protecting the needle after use is the use of a tubular shield that can be telescoped relative to both the hub and piercing element from a proximal position where the piercing element is exposed to a distal position where the piercing element is safely within the tubular shield. Shields of this type typically include means for releasably holding the shield in its proximal position and for holding the shield more securely in its distal position. Some devices include a spring for generating relative movement between the shield and the piercing element. In some instances the piercing element is withdrawn proximally into the shield.
However, this prior art method requires movement of the hands of the medical provider toward the exposed needle and therefore may allow needle stick injuries during the recapping.
IN addition, a small volume of blood or other bodily fluid may remain in or on a piercing element after the piercing element has been withdrawn from the patient or when a catheter is removed from a patient. This residual fluid may splatter as the piercing element is retracted rearward into the prior art shield. In general, the larger the bore of the needle, the larger the acceleration of the needle in the proximal direction, and any transverse acceleration may result in the splatter of the residual bodily fluid.
The prior art has worked to reduce the likelihood of such splatter. In one example, an indwelling injector needle assembly has the hub slide along an inner periphery of the holder between a first position near the distal end of the holder and a second position near a proximal end of the holder. The latching mechanism is formed in and disposed between the hub and the holder so that the hub is inhibited from moving from the first position toward the second position, and vice versa. The needle edge can be retracted within the holder while remaining fixed to a patient's skin.
However, this form of the prior art has at least one problem. This structure includes a non-rotating needle. As is known in the art, a rotatable needle is preferable to a non-rotatable needle in order to maximize blood or fluid flow to or from a vessel in which the needle is inserted. The prior art device prevents the needle from being rotated after cannulation. The needle and hub cannot rotate relative to the cylindrical holder due to the lug being slidably engaged with the guide groove in the hub. Therefore the needle cannot be rotated when needed after cannulation in order to maximize blood or fluid flow to or from the vessel.
Another prior art device describes a system which provides a snap-on exterior mounted enclosing guard can be added to a needle assembly. A spring forms an essential element of this safety needle assembly. In particular, the spring includes an turned in flange which is described as imperforate, such that it acts as a blocking flange. The enclosing guard, by way of the imperforate blocking flange, upon the withdrawal of the needle from the blood donor or patient, blocks the contaminated needle point.
Thus, this prior art device is limited in its use of materials and design in that the flange must be imperforate in order to prevent the needle tip from coming into contact with any worker. However, the enclosing guard is in proximate relation to and actually touches the needle cannula while it is being withdrawn from the patient. Thus, this assembly can become contaminated itself. Although the needle point is blocked, the system may still contaminate the worker by the blood or fluid which is on the enclosing guard.
Thus, what is needed is a safety needle device that allows for the maximum blood or fluid flow to or from the vessel, and overcomes the limitations of the prior art.